Protractor-triangle.



R. F. ALLIN.

PROTRAGTOR TRIANGLE.

APPLICATION FILED MAY 11, 1912.

1 046,365. Patented Dec. 3, 1912;

UNITED ST PATENT OFFICE.

mcm'an r. arm, or NEW YonK}. N.. Y.,' ASSIGNOR T0 EUGENE nmrzenn 00., A

conrona'nqn or rumors.

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Patented Dec. 3, 1912.

Application filed m 11, 1912. Serial No. 696,644.

To all-whom it may concern:

Be it known that I, RICHARD a citizen of the United States, residing in the borough of Manhattan, in the city of New York and State of New York, have invented certain new and useful Improve- 'ments in- Protractor-Triangles; and I do hereby declare the following to be a full clear, and exact description of the 'nv tion, such as will enable others skilled [in he art F. ALLIN,

to which it appertains to make and use the same. 1

The present invention has relation to an I improved instrument of great simplicity and bygan angle may be accurately laid off from {,a base line and the secondside of the angle may be capable of being made at small cost, whereaccurately drawn without change of of the instrument.

are some of the advantages It supplies a convenient position The following of my invention.

combination'of triangle and protractor ofsuch a nature that any desired angle may.

be laid off from agiven point on a base hne in any quadrant of a circle, with the triangle in one'position. It provides a form of instrument wherein lines of maximum length may be drawn at suitable angles to one another in proportion to the size' of the triangle. It provides an instrument which remains accurate in spite of-the wear which may be expected from ordinary accidents,

7 incident to use.

While the invention broadly considered is.

capable of use with a protractor of less than a quadrant, in its preferred form'and in order to carry out its advantages to the-utmost, a right angled-triangle is used with a graduated quadrant, having its center near the apex of the right angle.

The instrument is shown in the drawing which is a face view of one side thereof.

The right angled triangle shown in the drawing, is made of transparent or translucent material,' and transparent in my claims covers either of these qualities.

A graduated quadrant is 'forme'd on one I orboth sides ofthe triangle and its center -tis'found atthe intersection of one of the as shown in the drawing a d the zero point :of the scale is found' where the quadrant in-v sides adjacent to the right angle with a" fineline 10 drawn preferably parallel to the other adjacent side. point is in a continuation of the fine line 10 otherwise arisefrom of the vertex, if thevertex itself were adopt The ninety degree tersects the same edge of the triangle as is intersected by the line 10. v

. As shown in the drawings one set of the numerals indicating every ten degrees from zero to ninety is an that side of thetriangle which is toward the observer,'whil'e the other numerals, shown reversed, are upon the other side of the triangle. This is for convenience in use of the triangle when turned over for laying off angles of various quadrants of the circle. In order to lay off an angle from the base line A-B in the first quadrant of the circle as shown in. thedrawing, the center of the quadrant is properly placed upon thebase line as shown and the triangle is rotated about the center until the base line is seen through the triangle intersecting the I quadrant on the proper reading, and it may be easily adjusted within a quarter of a degree. It is obvious that in this position his only necessary to draw-a1 along that edge of the triangle whic 'sected bythe fine line 10 in order to the desired angle, out finding any preliminary point and without any movement of the triangleafter securing the proper reading.

It is obvious that any angle may be laid off in the first quadrant of a circle and in the third quadrant with that face of the triangle upward which is toward the observer 1 in thedrawing. v Inorder to lay off a desired angle in the 'second andfourth quadrants, the same procedure is adopted but the triangle is reversed so that the readings aretaken with the numerals'which are shown reversed in the drawing.

It will be observed that'the placing of the centerof the graduated arc off-set from the vertex of the triangle, makes it convenient todraw the entire line desired from the center outward and also avoids the inaccuracy as to the location of the center, which would ed as the center. 7 What I claim is-- 1. An instrument for y and this can be d0ne.with-- vol wearing and blunting;

laying off anglescoii i sisting of a'triangle marked with-a graduated circular are having its center near the vertex of one of the angles formed by the outside edges thereof and also provided with a .inark slightly off-set from saidvertex indicating the true center substantially as described.

2. An instrument for laying 0E angles consisting of a triangle made of transparent material marked With a graduated circular are suitably numbered on both sides from the; same zero end, said are having its center of said are,

near the Vertex of one of the angles of said triangle, and also provided With a fine line intersecting one edge of the triangle at such center, substantially as described.

3. An instrumentfor laying ofi angles consisting of a right angled triangle made of transparent material marked With a gradu- 'ated quadrant suitably numbered on; both sides fromthe same zero end at its intersection With one edge of the triangle, the center of said quadrant being marked at a point otfset from the vertex of the right angle along the aforesaid edge '01: the triangle, substantiallyas described.

In testimony whereof, I allix my signature, in presence of two Witnesses.

RICHARD F. ALLIN.

Witnesses WM. S. SYNIUFFENQ 

